In double-hung windows having upper and lower sashes that are movable independently of each other, a typical occurrence is that the upper sash settles or lowers from its fully raised closed position. This can occur, for example, when the upper sash balance springs are not strong enough to hold the upper sash closed, or when closing and locking the lower sash tends to pull the upper sash downwardly. A general object of the present disclosure is to provide a releasable detent arrangement for latching the upper sash in its fully raised closed position while at the same time permitting selective lowering of the upper sash.
The present disclosure embodies a number of aspects that can be implemented separately from or in combination with each other.
A building window in accordance with one aspect of the disclosure includes a generally rectangular frame having an upper rail and opposed side rails. An upper sash and a lower sash are independently movably mounted in the frame. A pair of opposed spring detents are mounted on the side rails adjacent to the upper rail of the frame. A pair of laterally opposed latches are at upper corners of the upper sash at positions to engage the spring detents as the upper sash is moved to its fully raised position. The latches cooperate with the spring detents to hold the upper sash in its fully raised position and are releasable from the spring detents to permit lowering of the upper sash.
Each spring detent preferably has a resilient arm positioned to be engaged by the associated latch as the upper sash is moved toward its fully raised position. The resilient arm preferably has a cam portion that is angulated and disposed to be engaged by the associated latch as the upper sash is raised. Each spring detent preferably also includes a second portion with a ledge for supporting the latch in the fully raised position of the upper sash. Each latch preferably includes a spring-biased latch bolt for camming the resilient arm of the spring detent laterally outwardly as the upper sash is raised and for resting on the ledge portion of the spring detent.